A new study that looks at the relationship between birth weight and academic achievement finds that heavier babies do better in school—and that an extra four pounds at birth could be worth 80 points on the SAT, the New York Times reports.
The study tracked every child born in Florida over an 11-year span, comparing their birth weight to standardized test scores through the eighth grade. The study also attempted to isolate birth weight as an independent variable by comparing the academic achievement of identical and non-identical twins.
Even in the case of twins—influenced by similar genetics and environmental factors—heavier babies tended to do better in school.
The findings may have an impact on the current trend towards inducing labor earlier.
Today, doctors generally feel comfortable inducing birth after a baby has reached 5.5 pounds and 39 weeks. But babies that spend additional time in the womb tend to gain more weight. If the strength of the relationship between birth weight and academic achievement stands up to further scrutiny, parents may have another reason to think twice about artificially inducing birth for non-medical reasons, according to the Times.
The authors of the study are quick to admit that birth weight may be a proxy for other measures of fetal health. However, birth weight and academic success were strongly correlated across all subsets of the authors' sample, suggesting weight alone plays a significant role in intellectual achievement.
For instance, of the students who scored in the top 5% on standardized tests in elementary school, one in three weighed at least eight pounds at birth, compared with one in four of all births.
The full study will soon be published in the American Economic Review (Leonhardt/Cox, "The Upshot," New York Times, 10/10).